Shallow-Water Coral Reefs in Transition: Examples from Belize and The Bahamas

Reprinted from: Ronald D. Lewis and Bruce C. Panuska (eds.) Proceedings of the 11th Symposium on the Geology of the Bahamas and Other Carbonate Regions: San Salvador, Gerace Research Cente

Population Recovery and Differential Heat Shock Protein Expression for the Corals \u3ci\u3eAgaricia agaricites\u3c/i\u3e and \u3ci\u3eA. tenuifolia\u3c/i\u3e in Belize

Over recent decades, coral reefs worldwide have experienced severe sea-surface temperature (SST) anomalies. Associated with an El Niño-Southern Oscillation (ENSO) event of 1997-1998, nearly 100% mortality of the space-dominated coral Agaricia tenuifolia was reported at several shelf lagoonal sites of the Belize barrier reef system; a less abundant congener, A. agaricites, had lower mortality rates. We assessed A. agaricites and A. tenuifolia populations at coral reef ridges in the south-central sector of the Belize shelf lagoon and forereef sites to document recovery following the 1998 ENSO event and subsequent passage of Hurricane Mitch. To investigate the difference in heat stress tolerance between the 2 species, heat shock protein (HSP) expression was examined in the laboratory under ambient (28˚C) and elevated (+6˚C) temperatures. Populations of A. agaricites and A. tenuifolia surveyed at forereefs sites in 1999 showed after effects from the 2 disturbances (partial colony mortality was ~23 and 30% for A.agaricites and A. tenuifolia, respectively), but partial mortality declined by 2001. At reef ridge sites, A. tenuifolia exhibited 75 to 95% partial colony mortality in 1999 compared to 18% in the less abundant A. agaricites. We measured a significant increase in percentage live cover at ridge sites for both Agaricia species from 1999 to 2001, except at Tunicate Ridge; at this site, which has restricted water flow, live A. tenuifolia cover remained low (~10%) 3.5.yr after the 1998 warming event, due in part to high sponge cover (\u3e75%). Immunoblotting results indicate that A. agaricites had twice as much HSC 70 (16.9 µg cm-2) as A. tenuifolia (8.7 µg cm-2) at ambient temperatures and 6x as much under the +6˚C treatment. In addition to the inducible response by A. agaricites, this species expressed HSP 90, whereas A. tenuifolia did not. The distinctive patterns of population recovery and HSP expression suggest that A. tenuifolia has a lesser ability to produce HSPs for protection against environmental stress than A. agaricites. Such differences in resilience to large-scale environmental disturbances such as intermittent ENSO episodes may drive a dramatic change in coral species abundance patterns

Assessment of Selected Reef Sites in Northern and South-Central Belize, Including Recovery from Bleaching and Hurricane Disturbances (Stony Corals, Algae and Fish)

The condition of coral. algal. and fish populations in fore reefs. patch reefs, and coral reef ridges was investigated at 13 sites along the northern and south-central Belize barrier reef during May 1999, documenting effects of the 1998 warming episode and Hurricane Mitch. We found high percentages of partial, or even complete, colony mortality of major reef-builders (Acropora palmata, the Montastraea annuluris species complex and Agaricia tenuifolia) that were rarely censused as recruits. A. tenuifolia, formerly a space-dominant coral in reef ridges, had incurred nearly 100% mortality after bleaching. Nearly 45% of the M. annurluris complex was still discolored (50% had been bleached in January 1999) on some south-central patch reefs where the total (recent + old) partial mortality exceeded 60% of colony surfaces. Although turf algae dominated patch reefs and coral reef ridges, macroalgae were quite prevalent representing \u3e30% cover at six sites. Parrotfish densities exceeded surgeontishes at most sites (11/13). Consistent patterns of lower partial-colony mortality of stony corals and greater fish densities and sizes near and within the Hol Chan Marine Reserve highlight the ecological benefits of protected areas for the maintenance of reef corals and attendant fish populations

Resilience and Recovery of Coral Reefs From Large-Scale Disturbances: Contrasting Patterns for San Salvador Island, Bahamas, and Belize

Benjamin J. Greenstein and Cindy K. Carney (eds) San Salvador, Gerace Research Cente

Assessment of Coral Reefs off San Salvador Island, Bahamas (Stony Coral, Algae and Fish Populations)

During assessments at 11 shallow reef sites on an Salvador Island, Bahamas in .iunc I998 we found low prevalence of disease, bleaching, and recent partial-colon1 mortality among stony corals (10 cm minimum dixncter). Old partial-colony mortalit) was \u3e50% in Acropora palmata; however, recent tissue losses were low and it had recruits at several sites. Total (recent + old) partial-colony mortality of the Montastraea annularis species complex exceeded 30% on leeward patch reefs and back reefs. Groupers (serranids), snappers (lutjanids), and grunts (haemulids) were rare. Parrotfishes (scarids) were uncommon at most sites and surgeonfishes (acanthurids) were the dominant herbivores. Macroalgae, particularly browns that are seldom grazed by surgeonfishes. were the dominant algal functional group. The green macroalga Microdictyon marinum was extremely abundant and overgrowing Porites porires on leeward patch reefs. To facilitate their conservation, an Salvador Island\u27s reef resources should be designated as a marine reserve